How does chronic stress contribute to illness and disease?
"Stress doesn't make you sick," says Esther Sternberg, M.D., chief of the Section on Neuroendocrine Immunology and Behavior at the National Institute of Mental Health (NIMH) and director of the NIMH's Integrative Neural Immune Program. "What makes you sick is your body's stress response, which changes the way your brain communicates and interacts with your nervous and immune systems. Disruption of the communication network can worsen the diseases that these systems guard against, including infectious diseases, inflammatory conditions, autoimmune disorders and mood disorders."
When the stress response is continually activated, it can lead to too much cortisol in the body. But an excess of cortisol blunts the immune cells' ability to fight infection. When your immune cells now encounter bacteria or a virus, the cells can't fight the pathogen and you end up getting an infection.
An excess of cortisol can affect your metabolism too. "When cortisol is continually being pumped out, it's continually mobilizing sugar from your liver. Now excess sugar builds up in your bloodstream; over time, that excess may contribute to metabolic syndrome, a condition that predisposes individuals to some of the top killers in America, including diabetes, obesity, osteoporosis, and cardiovascular disease."
Sometimes it's not the supply of cortisol that's affected, but the ability of your immune cells to respond to cortisol. It's called tissue resistance, and researchers aren't sure why it happens. Tissue resistance contributes to inflammatory illnesses such as rheumatoid arthritis, allergic diseases like asthma and dermatitis, fatigue conditions like chronic fatigue syndrome and fibromyalgia and mood disorders like seasonal affective disorder.